For brevity, the following summary is focused on, but not limited to, photovoltaic (PV) systems that produce DC electricity directly from the sun's rays shining on PV modules that contain a number of interconnected solar cells. The electrical conductors that carry DC output from PV modules are conventionally connected to metal lugs in a “junction box” located on the back of the PV module. Several PV modules are often combined to aggregate the current or voltage in what is commonly called a PV string where several individual PV modules are joined by one or more electrical connectors that provide connectivity, usually in a series fashion. Several PV strings are often further joined by downstream connectivity components, such as a combiner box that aggregates the electrical power. Several combiner boxes are often connected in a tree-like fashion to large combiner boxes (sometimes called re-combiners) for aggregating power into a transmission line. In practice, one or more combiner boxes include over-current protection and isolation means, such as relays and breakers and insulated levers to deal with overloads and isolate short circuits.
Briefly stated, the present invention is a pro-active device to provide disruption of electrical connectivity without need for electrical devices.
In the case of an arc happening within connectivity, such as that of a PV system, the intense heat generated can result in a localized fire of combustible material used in the connectivity's construction and quickly spreads to proximal combustible materials.
The problem of arc faulting in PV connectivity is so serious that the Fire Protection Association (FPA) modified the 2014 National Electric Code (NEC) section 690.11 (listed as Reference #1 in the LIST OF NON-PATENT DOCUMENTS):                “Photovoltaic systems with DC source circuits, DC output circuits, or both, operating at a PV system maximum system voltage of 80 volts or greater, shall be protected by a listed (DC) arc-fault circuit interrupter, PV type, or other system components listed to provide equivalent protection. The PV arc-fault protection means shall comply with the following requirements:                    (1) The system shall detect and interrupt arcing faults resulting from a failure in the intended continuity of a conductor, connection, module, or other system component in the DC PV source and DC PV output circuits.            (2) The system shall require that the disabled or disconnected equipment be manually restarted.            (3) “The system shall have an annunciator that provides a visual indication the circuit interrupter has operated. This indication shall not reset automatically.”                        
The present invention differentiates from electrical arc fault protection devices that operate by detecting noise, radio frequency, light of plasma, radio, and other electromagnetic emissions of an electrical discharge. The approach of previous art is limiting, as it requires an arc-fault to be present before remediation is possible. Lightning bolts during storms result in false alarms. Other prior art use information from thermal sensors, infrared sensors, and cameras as a means to detect heat, an active arc, or a fire. However, such means are not-proactive and cannot detect initiation of an arc or fire in places obstructed from view.
Arc detection devices include circuit breakers, ground fault interrupters (GFI), arc fault detectors (AFD), and arc fault circuit interrupters (AFCI) which act to mitigate electrical safety hazards. Stopping the current flow is not always effective because the intense heat of the plasma generated by an electrical arc can cause either immediate fire or embers which ignite at a later time and spread to the supporting structure or nearby flammable material. GFI, AFD, ACFI, and circuit breakers do not pre-empt direct current arcing and cannot completely interrupt DC current at the source when the source of energy is unstoppable, as is the case with solar energy.
Arc faults in PV modules and PV connectivity are often caused by defective installation, and factory defects are widely documented. Ohmic heating caused by oxidation can also result in arc faults, as documented in the 2015 Sandia Laboratory Technical Report authored by B. Yang, K. Armijo, E. Schindelholz, K. G. Blemel, K. D. Blemel, J. Johnson, “Photovoltaic Balance of System Connector Arc Fault Prognostics through Optical Monitoring,” (SAND2015-0883, which at the current time is not available in the public domain, “For Official Use Only” (FOUO), withheld from pubic release.) Ohmic heating due to corrosion or loose connections can also occur injunction boxes, combiner boxes, inverter boxes, and protection within the electrical distribution system. The ohmic heating may also degrade the conduction path in a manner that when sufficient energy is present, an arc fault can be established in the conduction path.
Human trauma and electrocution can result by touching the metal frame and/or an associated electrically conductive structure of a system component, which is electrified by an arc fault. When the supporting energy of the arc fault is DC, there are no zero-crossings as in alternating current and the arc does not self-extinguish, but continues as long as sufficient energy exists.
The Underwriter Laboratory 1699B Standard (in reference #7 in the LIST OF NON-PATENT DOCUMENTS, which is incorporated in its entirety by reference) requires DC arc-fault circuit protection devices intended for use in PV systems to mitigate the effects of arcing faults that may pose a risk of fire ignition under certain conditions if the arcing persists, because even though the electricity in the connectivity downstream from the PV module is shut off, the very hot plasma is likely to have caused conflagration of proximal combustibles in the module.
There is a pressing need for an improved means described in detail in the present invention that acts autonomously to take action to prevent arc-faults from happening. It would therefore be desirable to provide an apparatus with means for pre-arc, unsafe-condition detection and mitigation therein that works even when voltages and currents are within normal limits. Further, the protection system would meet the NEC Section 690.11 and other NEC requirements by annunciating unsafe conditions in PV system equipment and associated wiring. The protection system would provide mitigation before the arc-fault occurs, shutting down the PV component with an unsafe condition; therefore preventing fire damage and human disasters by properly isolating only the unsafe component in a safe manner and alerting the system owner or consumer for replacement or reinstatement.